There is currently known in the prior art various devices and methodologies for infusing therapeutic fluids directly into an anatomical passage (e.g., a vein or artery) of a patient. Medicaments or therapeutic fluids are typically sold to hospitals in flexible, transparent partial fill bags which are often referred to as "minibags". These partial fill bags are generally provided with a first outlet port for allowing a tubular fluid line to be fluidly connected thereto, and a second outlet port which serves as an injection site for allowing a needle or other type of piercing tip to be extended into the interior of the bag.
One of the most common methods of accomplishing direct fluid infusion into an anatomical passage is through the use of a conventional intravenous (IV) drip unit. Such drip units comprise a fluid filled IV bag which is suspended from a portable hanger assembly. Fluidly connected to the bag and extending therefrom is a tubular fluid line, the distal end of which typically includes an introducer needle connected thereto. In these prior art units, the fluid "drips" from the bag into the tube connected thereto, with the drip rate being adjustable to control the rate at which fluid is introduced into the anatomical passage. The bag is suspended well above the level of the introducer needle, with flow through the fluid line being facilitated by gravity.
Though these prior art IV drip units accomplish their intended objective of infusing therapeutic fluids into the anatomical passage of a patient, they posses certain deficiencies which detract from their overall utility. Foremost of these deficiencies is the inability to accurately control or meter the rate at which fluid is infused into the patient. As such, prior art IV drip units are frequently only employed when large volumes of a therapeutic fluid are to be infused into a patient, with the rate of infusion not constituting a critical parameter.
In recognition of the deficiencies associated with conventional IV drip units, there has been developed in the prior art various mechanical and electromechanical infusion devices which are adapted to provide a more controlled rate of infusion of a medicament or therapeutic fluid into an anatomical passage.
One such prior art device which is marketed and sold by the HealthTech Corporation comprises a spring biased syringe having a flow control orifice. The syringe comprises a plunger member which includes an elongate stem releasably attached to a two-part plunger head having a biasing spring extending between the parts thereof. The stem is pulled relative to the syringe body (which defines the flow control orifice) to facilitate the drawing of a therapeutic fluid into the body. Once the syringe body has been filled to a desired level, the rotation of the stem facilitates the detachment thereof from one part of the plunger head, with such detached part thereafter being biased toward the outlet orifice of the syringe body by the biasing spring. The force applied to the detached part of the plunger head by the biasing spring facilitates a controlled rate of flow of the fluid from the syringe body via the orifice.
However, this spring biased syringe also possesses certain deficiencies in relation to the controlled rate of flow of the therapeutic fluid therefrom. In this respect, the force exerted against the detached part of the plunger head by the biasing spring is not constant throughout its entire length of travel. Rather, as the compressed biasing spring is extended, the biasing force exerted against the detached part of the plunger head thereby proportionally decreases. As such, the flow rate of therapeutic fluid from the syringe body typically decreases as the fluid volume within the syringe body decreases.
In addition to the foregoing, the prior art spring biased syringe must be disposed of after each use, thereby increasing the costs associated with its use. Moreover, the use of the spring biased syringe necessitates that the therapeutic fluid be transferred from the partial fill bag into the syringe body. As will be recognized, this transfer procedure increases the risk of inadvertent fluid contamination, and requires additional, undesirable handling of the therapeutic fluid.
Another prior art infusion device which is marketed and sold by Secure Medical, Inc. under the trademark Med Flo and is the subject of U.S. Pat. No. 4,953,753 comprises a hollow housing or reservoir having a fluid inflatable bladder or balloon disposed therein. The balloon is filled with a therapeutic fluid via an inlet check valve communicating therewith. Fluidly connected to the end of the balloon opposite the inlet check valve is a tubular fluid line which includes a fixed orifice flow control fluidly coupled therewithin. The filling of the balloon with the therapeutic fluid causes the resilient expansion thereof within the housing. In this respect, the resiliency of the balloon forces the fluid into the fluid line, with the rate of flow through the fluid line being regulated by the fixed orifice flow control therewithin.
This infusion device, like the spring biased syringe previously described, also possesses deficiencies which detract from its overall utility. In this respect, this prior art device must also be disposed of after each use, thereby increasing the costs associated with the utilization thereof. Additionally, the use of this device also requires that the medicament or therapeutic fluid be transferred from a partial fill bag into the inflatable balloon via a separate transfer procedure. As previously indicated, such transfer procedure increases the risk of fluid contamination
Another prior art infusion device is sold by the I Flow Corporation under the trademark SideKick 100 and comprises a hollow housing having a cap including a spring biased plate threadably engaged thereto. Disposed within the housing is a circularly configured bladder which is inflatable with a therapeutic fluid. Subsequent to the placement of the filled bladder within the interior of the housing, the cap is engaged thereto which facilitates the application of compressive pressure to the bladder via the spring biased plate of the cap.
However, as in the previously described prior art syringe, the pressure applied to the bladder by the spring biased plate of the cap threadably engaged to the housing is not constant, but rather decreases as the fluid volume within the bladder decreases. Additionally, though only the bladder need be disposed of after each use of the device and both the housing and spring plate cap may be reused, the utilization of this device still necessitates that the therapeutic fluid be transferred from the partial fill bag into the bladder.
In another prior art electromechanical infusion device, a conventional syringe filled with a therapeutic fluid is placed into a housing, with the plunger member of the syringe being coupled to a movable actuation mechanism. The device is programmable in a manner regulating the speed at which the actuation mechanism forces the plunger into the syringe body, and hence the rate at which fluid is dispensed from the outlet end of the syringe body. However, this particular electromechanical infusion device is extremely expensive, and requires specialized training for its programming and use. Additionally, once again, the therapeutic fluid must be transferred from the partial fill bag into the syringe which is subsequently placed into the device and coupled to the actuation mechanism.
As previously discussed, perhaps the largest deficiency associated with the prior art infusion devices is the necessity of having to transfer the therapeutic fluid from the partial fill bag into the device. Additionally, the prior art mechanical and electro-mechanical infusion devices tend to be extremely costly, with current insurance regulations providing for decreased levels of insurance reimbursement associated with their usage. Moreover, these prior art devices typically do not provide for a highly controlled rate of fluid flow, with certain ones of these devices requiring specialized training for their use thus further increasing the costs associated therewith.
The present invention overcomes the deficiencies of prior art mechanical and electromechanical infusion devices by providing a device which is adapted to accommodate standard, off-the-shelf partial fill bags, thus eliminating the necessity of having to conduct a separate fluid transfer operation. Additionally, the infusion device constructed in accordance with the present invention is substantially less costly to manufacture than those known in the prior art, and provides an extremely accurate, controlled rate of fluid flow.